Machine for testing and classifying tubes closed at one end



April 10, 1951 D. G. ASHCROFT ETAL 9 mcnm: FOR 'rss'rmc AND CLASSIFYING TUBES cwssn AT ous END Filed Jan. 7, 1949 FIG.2.

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AQ'T 20 I x 22 Inventors DONALD GEORGE ASHCROFT IAN FRASER-STEWART Attorneys M M M cam 8 mounted on the axle 2.

Patented Apr. no, 1951 MACE FOR TESTING AND CLASS :I':

TUBES CLOSED AT ONE END Donald George Ashcroft, Saltcoats, and Ian Fraser Stewart, Kilwinning, Scotland, assignors to Imperial Chemical Industries Limited, a corporation of Great Britain Application January 7, 1949, Serial No. 69,776 In Great Britain February 23, 1948 The present invention relates to a machine for testing andclassifying tubes of relatively greater of testing and classifying readily and efficiently a large number of tube in a working day.

Other various objects and purposes of "this invention will become apparent from the fol lowing description taken in conjunction with the drawings, wherein:

view in cross .tially radially in the cylindrical member l are actuated during its rotation by a stationary Each of these syringes 3 is provided with a hollow needle 01 pin 5 for receiving a tube 6 to be tested. As shown, the spring 4 is in it compressed condition in cam-operated syringe 3 and in its extended condition 4' with cam-operatedsyringc -3'. In the latter extended position brought about by the low dwell 20 of earn 8, a vacuum is created within a non-defective tube 6 when in its proper position against the seating I by the exhaust of air through the needle 5.

The tubes 6 are fed to their testing position about the needle 5 by means of a feed pipe H .having a cocking lever l2 which frictionally retains all of the stacked tube 6 within the feed pipe ll except for the last tube which is normally held in the tube in the position shown by trip lever l3. Upon rotation of the cylinder I,

tripping pin I4 first actuates trip lever l3 permitting the one lower tube to descend by gravity in position over the needle 5, the remaining tubes 6 being held in position by the frictional engagement of the end of cocking lever I2 with the lower tube of the same, and upon further rotation of the cylinder l tripping pin l4 passes by the end of trip lever l3 permitting it to close 11 Claims. (CI. 73-43) the end of feed pipe H and then actuates cocking lever l2 to permit the tubes to fall downwardly and thereby present a tube'for positioning in the next syringe opening.

v A rubbing shoe 9, which is of spring steel in its preferred form, is provided so that the tube undergoing tests can be held well against seating I while suction is initially applied. This rubbing shoe 9 presents its convex surface towards the periphery of the cylindrical member I I and as the tube 6 passes underneath the shoe it is forced against the seating I. The shoe as shown is positioned at approximately top dead center andcontact is brought about at the time or just before the syringe piston is pulled downwardly by the action of the low dwell cam portion 20.

It is further desirable to provide a shearing blade l5 for cutting off tubes 6 of excess length before they approach the rubbing shoe 9. Also, it is desirable to provide a shoe 18 to protect the trip lever 13 from being damaged by a tube 6 accidentally carried beyond its ejection position, i. e., when the syringe carrying such a tube has just passed beyond its bottom dead center position and proceeded into the area of the high dwell cam surface l9 normally causing breaking of the vacuum which retains the tube 6 in its position during rotation from top dead center to bottom dead center.

As shown, one preferredv form of mounting the syringes 3 radially within. the cylindrical member l is by meansof sockets I6 which are provided with syringe retaining cap I! having bearing surfaces I0. As shown in Figure 3, a projecting surface on the syringe retaining cap I! applies a force to the tube 6 to exactly counter act the oppositely directed force occasioned by the friction between shoe 9 and the top of the detonator tube 6 which tends to tilt the tube backwards off of its seating 1.

Further, during the actuation of the syringe pistons of syringes 3 by the stationary-cam 8 as they pass from the high dwell surface I9 over the slope 2| to the low-dwell surface 20 and back to the high dwell surface 19 over slope 22, a recess 24 is provided which assures that springs 4 will return to their compressed position and thereby completely break the suction.

It is seen from the above description that the present invention provides a machine for testing and classifying tubes of relatively greater length than diameter and closed at one end, such as detonator tubes, by means of suction. In the preferred form of the machine, as illustrated. the

cycle of operation is asfollows: As any given syringe l rises towards the top dead center, a detonator tube is fed mouth first over the hollow needle or test pin Ii. At and around the top dead center the tube is held squarely on its seat by the combined action of the fixed spring shoe 9 and a bearing surface Ill on the face of the syringe retaining capl1. Suction is applied when the tube under test is being held on the seating I and so the desired joint is made between the detonator tube and the seating. It is important that the suction is sufliciently great to overcome any distorting effect due to vibration of the shoe 9. From this position until the suction is broken at about the bottom dead center by the high dwell portion I! of cam 8, the conditions are not altered and the tube, if non-defective, is held on its seat until it is discharged into an appropriate receptacle; If, however, the tube is faulty the joint is not made in which case the tube is discharged prematurely into its rejects" box.

As the tube faults must cause a break in the suction if they are to be rejected by the machine, the testing points must be designed so that as many tube faults as possible will have this effect. Defective tubes which can be detected because suction cannot be established in spite of contact being made with the seating are holed tubes, split tubes, "cut-throat tubes, incomplete tubes, tubes with ragged mouths, tubes with non-cylindrical mouths, and telescoped tubes. Defective tubes which can be detected by the test pin or hollow needle because the mouth of the tube is prevented from reaching the seating are double bottom tubes, short tubes, and tubes with scrap in the bottom.

. The tubes to be tested may also be such as to have scrap stuck inside them not very close to Such tubes will 1 the bottom or very long tubes. project so far out of the test chamber as to be a danger to the rubbing shoe. This danger'is re moved by the provision of a shearing blade l5 as described above.

The nature of the material used for the construction of the seating I is of importance. If rubber is employed for the seating it has been found that both the softness .of the rubber and the thickness are deciding factors. In order to form a successful seal at least a minimum distortion of the seating is required. This distortion involves a greater force on the seating for thinner as well as for harder rubber. This force is exerted upwards by the seating to balance the push exerted by the shoe 9. When the syringe has passed beyond the shoe this force must be balanced by the suction or the strain energy stored in the seating will release itself and throw 05 the tube thereby spoiling the test. It has been found that for soft rubbers of high quality a; of an inch and upwards are suitable thicknesses for the seating when detonator tubes are being tested. Thinner seatings or washers resist the suction holding force too vigorously, the strain energy being concentrated in asmaller space and the distortion force rising to excessive pro.- portions. To prevent the sharp edges of the detonator from being forced between the seating and the pin when the pin projects through the seating it is desirable to recessthe pin by turning it to a smaller diameter corresponding in length to the thickness of the seating. The seating is also cut with a smaller hole so that it occupies the recess. It is also desirable that the washers forming the seating should be conical or spherical in shape so that radial faults as spotted and rejected by the machine.

' It is also desirable that the pins 5 of the syringes 3 be of a very small diameter so as to prevent the machine from having to be stopped due to a dented tube gripping the pin and failing to be discharged.

The description of the foregoing invention as illustrated by the drawings is believed to fully set forth the operation of the same along with the advantages resulting from its use. The drawings, however, are illustrative of only one form of the invention and applicants contribution to the art is not to be limited thereby. The scope of the invention is set forth in the following claims.

We claim:

1. A machine for testing and classifying by means of suctiontubes of relatively greater length than diameter and closed at one end comprising a cylindrical member adapted to rotate about a fixed horizontal axis, a plurality of piston operated syringes mounted substantially radially .in said cylindrical member, each of said syringes being provided with a hollow needle adapted to receive thereon a tube to be tested, a tube seating positioned around each of said needles at a distance from the end thereof permitting the open ends of tubes of a predetermined standard length to make contact with said seating, and a stationary cam mounted on said horizontal axis adapted to actuate each of the pistons of said syringes for producing a vacuum in non-defective tubes and thereby retaining them on said seating during a portion of a cycle of rotation of said cylindrical member.

2. A machine as set forth in claim 1 provided with a rubbing shoefor initially seating a tube under test and thereby assuring the retention of non-defective tubes upon the initial application of vacuum.

3. A machine as set forth in claim 2 wherein each syringe has a retaining cap provided with a bearing pad for counteracting the tilting force of said rubbing shoe.

4. A machine as set forth in claim 1 wherein initial application of vacuum.

5. A machine as set forth in claim 1 wherein each piston-operated syringe is provided with a spring which normally forces said piston outwardly in a position for producing a vacuum.

6. A machine as set forth in claim 1 wherein the shape of said cam permits the application of a vacuum to a tube upon passage of the tube from top dead center to approximately bottom dead center, the vacuum being released after passage from the bottom dead center toward the top dead center.

'7. A machine as set forth in claim 1 wherein the hollow needle is recessed by having been turned to a smaller diameter corresponding in length to the thickness of the seating.

8. A machine as set forth in claim 1 wherein the seating is conical in form.

9. A machine as set forth in claim 1 the seating .is spherical in form.

10. A machine as set forth in claim 1 wherein a'feeding device is provided for placing the tubes accurately over the seating, the said feeding device comprising a feed pipe having tripping v wherein REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 725,589 Rehfuss Apr. 14, 1903 1,090,235 Rogers Mar. 17, 1914 1,332,516 -0Donne11 Mar. 2, 1920 10 2,278,804 Stuart Apr. 7, 1942 2,352,916 Schrader July 4, 1944 

